Rugh Idle and miss

[87grandnational]

Sounds exactaly like my car... My car has a miss, and a white substance comming out the pipes... I have no clue why... ECM maybe? TPS? or MAF

 

[darkred87T]

I'm not familiar with the white substance problem but I did repalce the MAF, swapped out ECM from my Brother's GN, and new TPS.

 

[darkred87T]

Thanks Phil. The car seemed bone stock when I got it. It blew alot of smoke from a bad turbo before the rebuild. Is it possible to have a problem with the throttle body or other comonents due to left over oil residue?

 

[darkred87T]

O.K, I took the car to Dynotech. They told me they fixed some vacume leaks, put one of their own chip in it and adjusted the translator. The car seems to idle better and IAC counts are up, (a little high, between 25-35).
Here's the remaining issue: The car still stumbles as it warms up every time in cold weather. When warmed up, driving down the road at a steady speed and letting off or goosing it and letting off, the RPM drops to 650 or so, then picks back up to 750-800. I can hear it stumble for a second, then pick back up. It always had this idle dip and I think it's what used to cause the car to stall. I don't know, I still think I have a vacume leak somewhere.

 

[VadersV6]

Originally posted by darkred87T
O.K, I took the car to Dynotech. They told me they fixed some vacume leaks, put one of their own chip in it and adjusted the translator. The car seems to idle better and IAC counts are up, (a little high, between 25-35).
Here's the remaining issue: The car still stumbles as it warms up every time in cold weather. When warmed up, driving down the road at a steady speed and letting off or goosing it and letting off, the RPM drops to 650 or so, then picks back up to 750-800. I can hear it stumble for a second, then pick back up. It always had this idle dip and I think it's what used to cause the car to stall. I don't know, I still think I have a vacume leak somewhere.

Do you have a high stall non lock converter? It almost sounds like DFCO (deceleration fuel cutoff) causing dips. If there isnt enough engine braking caused by a high stall converter, there isnt enough of a reverse load seen to shut fuel off during deceleration. If the speed is high enough, there is enough braking to work. Thats when there is fuel cutoff, and the rpms dip. Then as you slow down further, the fuel cutoff stops, it starts fueling again, and the rpms jump up. Do you have a scanmaster? I have a slight issue with this. DFCO only works at speeds above 60-65 with me. If I let off at that speed, my o2 millivolts drop to zero, but once I get down to about 55, it starts fueling again. Ive used DFCO delay with my extender chip, but all it does is raise the speed where DFCO works. My rpm's dont dip enough to stall, so I just left it alone.
I also have a bad idle issue. Ive replaced/adjusted everything thats connected to closed loop..i.e., all sensors. It hasnt made a bit of difference in my idle quality. Only thing that helped substantially, was switching to open loop idle. But I hate having to do that. Its a real bandaid approach to getting the car running right.
Anyway, Ive had an extremely close symptom to what you're experiencing, and it was the cam sensor. I just needed to rotate it slightly CClockwise, even though I had adjusted it perfectly to spec.

 

[copo]

I had a rough idle when cold and it spit when I tried to floor it and was better when it was warm except for the miss feeling at idle.

I ended up getting TB spray cleaner and removed the top turbo pipe to the TB and gave 3 long shots of spray, then connected the pipe back without tightening the clamps, started the car and ran it for 20 sec, then shut it off, removed the pipe then gave it 3 long spray shots again (do the sides, rear and the bottom), then connected the pipe back up and ran the car for 20 sec. etc.

Then I started the car up with the pipe still off and keeping the rpms up with one hand, I sprayed and sprayed and sprayed. Then I buttoned it up and went for a drive and gave it a couple of shots of WOT to blow any crap out. Before I went for a drive I disconnected the + side of the batt so the computer would have to learn the driving habits again from scratch.

My idle is fixed without doing any checking of the iac and tps using a multimeter if that's all you have. Just follow the directions here if your still idling bad.

http://www.gnttype.org/techarea/faq/IACresetscan.html
http://www.gnttype.org/techarea/maintenance/TPS.html

 

[darkred87T]

Originally posted by VadersV6
Do you have a high stall non lock converter? It almost sounds like DFCO (deceleration fuel cutoff) causing dips. If there isnt enough engine braking caused by a high stall converter, there isnt enough of a reverse load seen to shut fuel off during deceleration. If the speed is high enough, there is enough braking to work. Thats when there is fuel cutoff, and the rpms dip. Then as you slow down further, the fuel cutoff stops, it starts fueling again, and the rpms jump up. Do you have a scanmaster? I have a slight issue with this. DFCO only works at speeds above 60-65 with me. If I let off at that speed, my o2 millivolts drop to zero, but once I get down to about 55, it starts fueling again. Ive used DFCO delay with my extender chip, but all it does is raise the speed where DFCO works. My rpm's dont dip enough to stall, so I just left it alone.
I also have a bad idle issue. Ive replaced/adjusted everything thats connected to closed loop..i.e., all sensors. It hasnt made a bit of difference in my idle quality. Only thing that helped substantially, was switching to open loop idle. But I hate having to do that. Its a real bandaid approach to getting the car running right.
Anyway, Ive had an extremely close symptom to what you're experiencing, and it was the cam sensor. I just needed to rotate it slightly CClockwise, even though I had adjusted it perfectly to spec.

I do have a locking torque converter. I never thought of that. My RPM dips seem to happen only at low speeds. It hasn't stalled yet since I had it to Dynotech, but still seems funny that it would do that. BTW, what is open loop idle, without the chip?

 

[darkred87T]

Originally posted by copo
I had a rough idle when cold and it spit when I tried to floor it and was better when it was warm except for the miss feeling at idle.

I ended up getting TB spray cleaner and removed the top turbo pipe to the TB and gave 3 long shots of spray, then connected the pipe back without tightening the clamps, started the car and ran it for 20 sec, then shut it off, removed the pipe then gave it 3 long spray shots again (do the sides, rear and the bottom), then connected the pipe back up and ran the car for 20 sec. etc.

Then I started the car up with the pipe still off and keeping the rpms up with one hand, I sprayed and sprayed and sprayed. Then I buttoned it up and went for a drive and gave it a couple of shots of WOT to blow any crap out. Before I went for a drive I disconnected the + side of the batt so the computer would have to learn the driving habits again from scratch.

My idle is fixed without doing any checking of the iac and tps using a multimeter if that's all you have. Just follow the directions here if your still idling bad.

http://www.gnttype.org/techarea/faq/IACresetscan.html
http://www.gnttype.org/techarea/maintenance/TPS.html

Thanks, I bought some GM Intake cleaner when I first bought the car and did that exact same thing. I don't know if TB cleaner is the same, but it's worth a try.

 

[VadersV6]

Originally posted by copo
I had a rough idle when cold and it spit when I tried to floor it and was better when it was warm except for the miss feeling at idle.

I ended up getting TB spray cleaner and removed the top turbo pipe to the TB and gave 3 long shots of spray, then connected the pipe back without tightening the clamps, started the car and ran it for 20 sec, then shut it off, removed the pipe then gave it 3 long spray shots again (do the sides, rear and the bottom), then connected the pipe back up and ran the car for 20 sec. etc.

Then I started the car up with the pipe still off and keeping the rpms up with one hand, I sprayed and sprayed and sprayed. Then I buttoned it up and went for a drive and gave it a couple of shots of WOT to blow any crap out. Before I went for a drive I disconnected the + side of the batt so the computer would have to learn the driving habits again from scratch.

My idle is fixed without doing any checking of the iac and tps using a multimeter if that's all you have. Just follow the directions here if your still idling bad.

http://www.gnttype.org/techarea/faq/IACresetscan.html
http://www.gnttype.org/techarea/maintenance/TPS.html

So what exactly were you spraying? Were you opening the throttle blade and spraying inside the plenum, or spraying right on the face of the blade and all around it? Then you had the pipe completely off, and sprayed all in the inlet while running?

 

[2 SLOW]

87grandnational

I could be wrong, but it sounds to me like the white substance is steam. As in water. Usually that comes form water getting into the cylinder, which would most likely be a blown headgasket.

darkred87T

Looks like you have tried a lot of things to find the problem with no success. I didn't see in this thread where you checked the compression or did a leak down test. You could have a bad cylinder. There is a remote chance of a flat lobe on the cam. If it cuts down the top of the lobe but doesn't grind down the base circle you wouldn't hear any lifter noise, but that could be a stretch for being the problem.

One thing you also might check is whether the EGR isn't bad. The best way to check it is to try another one you know is good off someone elses car. To buy one is over $60. Also do the same with the EGR module. That is the black box over cylinder number five with the hoses coming from the EGR valve to the module. I have a 93 Typhoon that drove me crazy with bad idle, stumble, boost that would vary at WOT, and so on. Tried everything with no success until I changed the EGR valve. We had tested it with air to see that the diaphram worked, and it did, so we thought it was ok. Don't bother testing it just try another one. If thats not it your back to square one, but it isn't any harder to try it than any of the other things you have tried.

HTH and Good Luck

 

[copo]

Originally posted by VadersV6
So what exactly were you spraying? Were you opening the throttle blade and spraying inside the plenum, or spraying right on the face of the blade and all around it? Then you had the pipe completely off, and sprayed all in the inlet while running?

First off get the stuff from GM or a Auto parts store for TB cleaner that is sensor safe. GM sells a product made by Wymns. Don't use Cleans.

I first removed the upper pipe to the TB and looseded the lower hose clamp so I can swing the pipe out of the way while I spray then swing back in to reconnect it loose without tightening the clamps.

So with the car not running I removed the upper pipe and sprayed around the front of the flaps with them closed, then opened the flaps and sprayed the top and bottom of the flaps ( you may need a tooth brush for real grime) and wipe around with a cloth infront of the flaps so it doesn't run down on any hot areas (or use a rag to catch any drips).

Then I opened the flaps to WOT and gave three 3-sec shots of spray inside past the flaps to the back of the TB.
Then connected the upper hose and started the car and ran it for 20 sec. Then shut it off.

Then removed the upper pipe again and opened the flaps to WOT and sprayed inside past the flaps on the right side with three 3-sec shots of spray. Then connected the upper hose and started the car and ran it for 20 sec. Then shut it off.

Keep doing this for each side of the TB. (rear, left side, right side, upper and lower areas). When your done check with a flashlight to see how clean the TB is.

THen I started the car with the upperpipe connected, then removed the upper pipe and kept the rpms up with one hand on the throttle and with the flaps opened up a bit (rpms not screaming but high enough so it won't stall). Just restart it with the pipe off if it stalls and get to the throttle to keep it revving. So while I'm revving it I'm spraying near the bottom of the flap where it's open, so the fluid gets sucked in. When your done check with a flashlight to see how clean the TB is.

Then go for a ride and hammer the pedal to the floor to blow out any loose crud.

BTW, it's still running rough when it's cold.


I may have to do this that was recommended from another post of mine.

well you can check your iac and tps no problem using a multimeter. its not a difficult or even really a time consuming process. just follow the directions here.

http://www.gnttype.org/techarea/faq/IACresetscan.html
http://www.gnttype.org/techarea/maintenance/TPS.html


My original problem I posted was I was getting oil in my upper turbo pipe that connects to the TB. I fixed that by changing the PVC valve. Maybe I have oil in the intercooler that's causing greef but when I check my upper pipe after driving it's dry as a whistle.

These cars are really pissing me off. I need to make a ALDL cable and hook it up to my laptop cause I have no other scanning tools for this car. I have tools for my Chevy 70 LT1 and a mutimeter for checking the volts for the above 2 links. I just hate to get into this in case it runs even worse and I hate to take it into a garage because 1/2 the time the guys don't know anything about these cars.

 

[copo]

Has anyone a real top view picture of a 87 GN showing all the component names with an arrow? Such as EGR module, EGR valve. I do have the exployed views and see these from the parts book but I think it would be nice to see all the parts labelled on an assembled engine. If someone has one then please send me an email....thx

I'm tempted to buy a 2005 Ford GT Stang http://www.automedia.com/autoReviews/2005/ford/mustang/rts20041201mg.asp?affid=. My GN is running crappy when cold .
It spits, and the tubo light bounces when I try and mat it.

How would I do this procedure http://www.gnttype.org/techarea/faq/IACresetscan.html with a voltmeter or can I?

I see I can use a VM here http://www.gnttype.org/techarea/maintenance/TPS.html

 

[darkred87T]

Originally posted by copo
Has anyone a real top view picture of a 87 GN showing all the component names with an arrow? Such as EGR module, EGR valve. I do have the exployed views and see these from the parts book but I think it would be nice to see all the parts labelled on an assembled engine. If someone has one then please send me an email....thx

I'm tempted to buy a 2005 Ford GT Stang http://www.automedia.com/autoReviews/2005/ford/mustang/rts20041201mg.asp?affid=. My GN is running crappy when cold .
It spits, and the tubo light bounces when I try and mat it.

How would I do this procedure http://www.gnttype.org/techarea/faq/IACresetscan.html with a voltmeter or can I?

I see I can use a VM here http://www.gnttype.org/techarea/maintenance/TPS.html

Wow, those symptoms sound familiar.

 

[darkred87T]

I went to the dealer, and they did not have anyhting for fuel injected TB. I also tried the autoparts store and they had Gumout TB cleaner but it wasn't recommended for turbos. How can I get the right stuff?

 

[copo]

Originally posted by darkred87T
I went to the dealer, and they did not have anyhting for fuel injected TB. I also tried the autoparts store and they had Gumout TB cleaner but it wasn't recommended for turbos. How can I get the right stuff?

The GM dealer here does not have a GM product but are selling One Shot by Wymns. The part # on my bll is 32755. And it's sensor safe. I can take a dig pic of the can later and put it on my site if you want.

 

[darkred87T]

Thanks, a pic would be helpfull but I can probably work with name brand and part#.

 

[copo]

I tried looking for it on the Web but couldn't find it. Not sure if I got the spelling correct on W...... I'll post a pick on my web site.

 

[copo]

Here is what the GM dealer sells because GM does not make their own product.

http://ca.geocities.com/mlvd@rogers.com/images/wynns_air_intake_cleaner.jpg

http://ca.geocities.com/mlvd@rogers.com/images/wynns_air_intake_cleaner_label.jpg

 

[darkred87T]

Thanks, I'll try it.

 

[copo]

I still find it hard to believe that with all the '86-'87 Intercooled GN's out there that we can't narrow down a simple bad idle and miss. Come on guys. These IC cars are 19 yrs old. These problems and fixes should all be in a database. It's a joke to see people still trouble shooting by buying and swapping parts and hoping the problem will go away.

Too bad these cars aren't as easy to pin point problems as my fellow Camaro gear heads. With a SB Chevy, it's this and it's fixed.

These 3.8 computer controlled sensor stuffed bodies are nothing but a pain in the BUTT !!!!!!!!!!!!!!!